Daytime running lights — retrofitting, installation, coding

• Increased fuel consumption as all headlamps and lamps are always switched on: Lighting is expensive as the headlamps and rear lamps require electricity and therefore use fuel! For a normal car with a gasoline engine, this is approximately 0.207 litres in increased consumption per 100 kilometers when the lights are switched on. Based on a mileage of 30,000 km per year, this approximately adds up to an extra 60 litres. As a result of this, the exhaust emissions of course increase accordingly too.
• The replacement rate of light sources is significantly increased: Switching the lights on permanently increases the wear and tear of bulbs. The service life of standard versions of H7 and H4 halogen bulbs (no + 50% or long-life bulbs) lies between 550 and 700 hours. In the event of continual operation, the replacement rate of the bulbs would be significantly increased. An LED daytime running light , on the other hand, has a service life of 10,000 hours and usually lasts as long as the car.
• Besides the material costs, there are the sometimes considerable costs of the replacement of the light source . In some cars, the bulb replacement takes a great deal of effort, as battery, air filter housing, headlamps, etc. must be removed first.
• The warning effect of low beam lights is smaller than that of special daytime running lights. Low beam lights typically are set to provide an optimal lighting of the road in darkness. The emitted light "descends" evenly, in order to avoid dazzling oncoming traffic. Daytime running lights, on the other hand, are designed to achieve an optimal and early perception of the car during the day. Their light intensity is limited (2 Lux at a distance of 25 m) so that the emitted light is not perceived as glare.

Compared to driving without lights, this may be a step in the right direction. However, as explained above, daytime running lights offer clearly superior visibility and energy savings. Some of these electronic kits also dim the low beam, in the case of one manufacturer even by about 50%. This means that the luminous flux, i.e. the total volume of light that is output by a light source, is reduced so much that it falls below the required minimum value. This is absolutely prohibited by law!

This is because headlamps receive their type approval for form, light source, and function. Daytime running light generated with the aid of electronics thus means an additional lighting function which was not considered during type approval. Therefore, the headlamp automatically loses its approval!

Generally, daytime running lights must be approved for road traffic. To obtain this, they must therefore fulfil the specifications according to ECE-R87. Once the light passes the so-called type approval, the approval is granted. Generally, the approval mark can be found on the lens or the housing.

Daytime running lights make a great contribution to safety in road traffic. Law makers are also convinced that this is the case. For this reason, this lighting function is obligatory for all new vehicles entering the market from February 2011 onwards. The market offers a wealth of retrofit solutions for vehicles which do not have daytime running lights fitted as standard.

There are few alternatives for electrical connection, despite the differences in terms of design, light sources, and attachment. With many manufacturers, the lights are connected with terminal 15 (switched plus, often also known as ignition plus), terminal 58 (position light) and terminal 31 (ground). While the connection of terminals 58 and 31 is unproblematic in most cases, the situation can be different for terminal 15.

In modern vehicles, there is a lack of connection possibilities under the hood e.g. fuses of other consumers connected to switched plus. In such cases, a cable has to be routed to the vehicle interior. There is usually a suitable connection possibility in the fuse box there. In many vehicles of the brands Audi, Seat, Skoda, and VW, daytime running lights can be triggered via the light switch.